1. Field of the Invention
This invention relates to a data printing device built into a camera, and more particularly to an improvement in data printing device for printing the photographing date or the like on the film when the picture is taken in a camera.
2. Description of the Prior Art
In a data printing device built into a camera, the optical axis of the optical system for printing the data on the film is normally inclined at an angle with respect to the line normal to the film face in order to save the space occupied thereby. Since the optical axis is inclined, it has been known in the art to provide a data carrying plate or the like in the position optically conjugate with the film face in order that the image of the date carried on the data carrying plate is is not of deformed shape on the film.
In the above described conventional data printing device, the magnifications of the image of the different indicia at different positions are different from each other since the distances of the different indicia from the lens in the printing optical system are different from each other.
In order to make the magnifications of the image of the different indicia at different positions all equal to each other, it is considered that one solution is to orient the data carrying plate or the like in parallel to the film face. Since the focal depth of the lens used in the data printing optical system is normally large, it is possible to obtain sharp images of the data on the film, even if the data carrying plate or the like is oriented to be parallel to the film face in the optical axis inclined at an angle with respect to the line normal to the film face.
However, the data printing device usually employs a set of data carrying plates consisting of several rotatable plates or discs which carry, for instance, days, months and years, respectively. The several rotatable plates are superposed and accordingly and positions of the indicia carried along the different plates are not on a plane which is precisely parallel to the film face. Therefore, even if the data carrying plates are oriented in parallel to the film face, the size of the data printed on the film is not uniform.